For example, in an inspection process for semiconductor devices, a prober has been widely used as a device for inspecting semiconductor wafers (hereinafter, simply referred to as “wafers”). Generally, the prober includes a loader chamber and a prober chamber to inspect electrical characteristics of the wafers.
The loader chamber has a carrier mounting unit for mounting thereon a carrier accommodating therein a plurality of wafers (e.g., 25 wafers), a wafer transfer mechanism (hereinafter, referred to as “arm mechanism”) for unloading the wafers from the carrier of the carrier mounting unit one by one, and a pre-alignment mechanism (hereinafter, referred to as “sub-chuck”) for aligning in advance the wafer transferred through the arm mechanism. With such arrangements, the wafers in the carrier are unloaded one by one through the arm mechanism and pre-aligned; and then transferred into the prober chamber.
The prober chamber has a mounting table (hereinafter, referred to as “main chuck”), moving along X, Y, Z and θ directions, for mounting thereon the wafers, an aligning mechanism for cooperating with the main chuck to align the wafers, a probe card disposed above the main chuck, and a test head interposed between the probe card and the tester. A number of probes of the probe card make contacts with an aligned wafer to inspect electrical characteristics thereof. Thereafter, the wafer is returned to the original place in the carrier from the prober chamber through the arm mechanism of the loader chamber.
In case of inspecting the wafer, an operator carries a carrier accommodating therein wafers to the carrier mounting unit of the loader chamber onto the carrier mounting unit. However, in case of a large diameter wafer of, e.g., a 300 mm wafer, the carrier accommodating therein a plurality of wafers is very heavy, thereby making it very difficult for the operator to carry such a carrier. Thus, there has been proposed in Japanese Patent Laid-open Publication No. H10-303270 a transfer method capable of transferring each carrier accommodating therein wafers of a same lot between an automatic transfer carriage and a processing equipment by using the automatic transfer carriage. In such transfer method, it is not required for the operator to carry the carrier; and therefore, the aforementioned problem can be resolved.
Meanwhile, with a recent trend towards a large diameter of the wafer and an ultra miniaturization of devices, the number of devices formed on a single wafer is significantly increased, so that much time is needed to complete a processing such as an inspection for a single wafer. For the reason, although the wafers of a same lot in a carrier can be transferred to a semiconductor manufacturing device such as an inspection device by using the automatic transfer carriage as described above, it takes considerably long time to process all the wafers in the carrier, and even wafers already processed have to stay in the semiconductor manufacturing device during such a process period. As a result, a subsequent processing for the wafers of the same lot is delayed, so that it is difficult to shorten a Turn-Around-Time (TAT).
To that end, the inventors have proposed a transfer system and method for transferring objects to be processed by using an optically coupled parallel input/output (I/O) communications in Japanese Patent Laid-open Publication No. 2002-217263. By this, it is possible to secure a transfer of objects to be processed, e.g., wafers, one by one between a first transfer mechanism of a plurality of semiconductor manufacturing devices and a second transfer mechanism of an automatic transfer device. Moreover, it is possible to parallel-process a plurality of objects to be processed by using the plurality of semiconductor manufacturing devices, resulting in a reduction of TAT for the objects to be processed.
In the transfer system and method disclosed in Japanese Patent Laid-open Publication No. 2002-217263, optical communications are carried out between the automatic transfer device and the semiconductor manufacturing device to actuate the first and the second transfer mechanism, thereby accurately and securely transferring the objects to be processed one by one. However, even in case where, e.g., two sheets of the objects to be processed may be consecutively transferred depending on an operation status of the semiconductor manufacturing device, the second transfer mechanism of the automatic transfer device cannot perform the transfer of the objects to be processed consecutively. For the above reason, a transfer efficiency of the objects cannot be always good. Further, since a sequence, control signal is transmitted via the optical communications between the automatic transfer device and the semiconductor manufacturing device to sequentially control the first and the second transfer mechanism, the communications are frequently carried out and a reduction in the communications time is limited.